The present invention relates to telecommunications systems, and in particular, to an improved telephony-over-LAN (local area network) system.
Modern telephony-over-LAN (ToL) systems allow each endpoint (e.g., client, gateway) to choose a default hierarchy of coding algorithms. For example, an endpoint might be configured to first try using adaptive pulse code modulation (ADPCM), next G.723, then GSM, etc., until a common codec supported by both the calling and called endpoints is found.
However, the endpoints or clients typically have static configurations of preferred codecs. As a consequence, network bandwidth is assigned on a simple availability basis, without regard to other users who might wish to place phone calls in the future. As a consequence, a few users who communicating using coding algorithms that result in high bandwidth consumption could use the entire network bandwidth, without even realizing bandwidth was in short supply, thereby preventing others from placing calls. As such, system bandwidth may be inefficiently utilized and even result in denial of service to some users.
While certain data modems, such as described in U.S. Pat. No. 5,546,395, allow for dynamic bandwidth adjustment between two communicating endpoints, by way of selecting the compression rates for voice transmission and the modulation rate, such systems do not allow for broad network-based supervision of bandwidth allocation.
These and other drawbacks in the prior art are overcome in large part by a coding algorithm policy adjustment system according to the present invention. A bandwidth adjustment server or bandwidth allocation server (BWAS) is provided which monitors system bandwidth usage, sends requests to user terminals to identify their coding capabilities, and directs each of the user terminals to adjust their coding algorithms based on system bandwidth usage. If system bandwidth usage is high, the BWAS requires the user terminals to employ a less bandwidth-intense coding algorithm; similarly, when system bandwidth usage is low, the BWAS will allow the user terminals to employ higher bandwidth-use coding algorithms.
The BWAS is configured with a first threshold identified as the threshold for reducing the coder/decoder (codec) speeds of the idle endpoints. The BWAS monitors system traffic, or communicates with other system monitors to determine system bandwidth usage. The BWAS sends a message to the user terminals, requiring them to identify their coding capabilities and the specific hierarchy used by them. Once this information is returned to the BWAS, the BWAS sends another message requiring the user terminals to lower their bandwidth usage by selecting a lower speed codec. When network traffic drops below a second pre-configured threshold, the BWAS sends another message allowing the user terminals to restore their original codec choices.